CMRO2 (DSC-PW) perfusion parameter helps to distinguish between progression and pseudoprogression in patients with glioblastoma.

Objective: To evaluate the diagnostic accuracy of CMRO₂ (cerebral metabolic rate of oxygen) in differentiating between pseudoprogression and true tumour progression in patients with glioblastoma (GB) following chemoradiotherapy and to compare its performance with rCBV (relative cerebral blood volume).

Materials and methods: This diagnostic accuracy study included two cohorts: an analysis group (32 patients, 19 progression, 13 pseudoprogression) and a validation group (52 patients, 35 progression, 17 pseudoprogression). Patients underwent MRI (magnetic resonance imaging) with DSC (dynamic susceptibility contrast) and DCE (dynamic contrast-enhanced) perfusion imaging. CMRO₂ and rCBV thresholds were evaluated to calculate sensitivity, specificity, and area under the curve (AUC). Inclusion criteria were GB diagnosis, standard chemoradiotherapy, and new or enlarged enhancing lesions on MRI within one year.

Results: In the analysis group (mean age, 60.8 ± 8 years), CMRO₂ showed superior performance with an AUC of 0.89 (95% CI 0.77-0.98), sensitivity of 84.2%, and specificity of 83.3%. rCBV achieved an AUC of 0.63 (95% CI 0.42-0.88). In the validation group (mean age, 63 ± 7 years), CMRO₂ maintained an AUC of 0.91 (95% CI 0.82-0.98), while rCBV reached an AUC of 0.79 (95% CI 0.65-0.91). The DeLong test confirmed CMRO₂'s significantly higher performance (p = 0.04).

Conclusion: CMRO₂ demonstrates higher diagnostic performance than rCBV in distinguishing pseudoprogression from true progression in GB patients. Despite limitations, CMRO₂ shows promise as a non-invasive biomarker, warranting further multicentre validation.